The present invention relates to a free electron laser device for conically scanning a spatial field and more particularly it relates to an improved free electron laser device for reflecting and steering various waves of a wave front so as to cause phase redistribution of the reflected waves that results in formation of asymmetric diffraction patterns and projection of a laser beam from the device to conically scan a spatial field.
Various techniques have been used in the past for generating relativistic electron beams and for magnetically exciting the beams so as to form a radiation wave front. Such techniques are exemplified by U.S. Pat. No. 3,822,410 to Madey that discloses an electron laser device. The device is generally made up of an accelerator for controlling the formation of an electron beam and a magnetic array for controlling the periodic excitation of the beam to form a radiation beam. Also, U.S. Pat. No. 3,731,106 to Mansel discloses a rotary mechanical beam scanner for deflecting various predetermined portions of a propagating wave front so as to facilitate an analysis of the high power laser generating the wave front. Similarly, a report of the Plasma Laboratory at Columbia University is entitled "Free Electron Lasers Based Upon Stimulated Raman Backscattering: A Survey" by T. C. Marshall. This report was presented at the Ettore Majorana Center, International School of Quantum Electronics, Irice, Sicily on August 1980. A laser device as disclosed on pages 12-13 of the report is considered pertinent. The device is generally comprised of a drift tube and a nonrotating mandrel which is disposed concentrically within the tube and which is provided with annular grooves. One of the primary purposes of the grooves is to reflect the radiation in order to enhance the coherence and stability of the radiation wave front as it propagates lengthwise of the tube and in a direction toward the outer end. The grooves form distributed feedback mirrors. However, neither the prior art nor the prior lab report, as discussed above, whether taken singly or in any combination, remotely suggest, among other things, an improved free electron laser device with a rotatable mandrel having a series of canted mirrors formed thereabout not only for redistributing the phase of various waves of the wave front so as to induce asymmetry therein, but also for steering the redistributed and asymmetric wave front so as to form a laser as it projects from the device outer end for conical scanning of a spatial field.